1. Field of the Invention
The present invention relates to a multiple pot for raising and transplanting seedlings and a method of fabricating the pot and, more particularly, to a multiple pot which consists of a number of individual pots used to raise seedlings and which promotes growth of roots extending across the side walls of the individual pot after the pot seedlings is transplanted in a field, reduces the resistance encountered when the multiple pot are unfolded. Also, the invention relates to a method of fabricating this multiple pot.
2. Description of the Prior Art
Pots consisting of a thin film of paper or the like have been widely used to raise crops. In particular, seedlings are raised within the pots and then transplanted to fields together with the pots, i.e., without removing the pots. Such pots are known as Paperpots. These pots which can be employed to raise and transplant crops take various forms. In recent years, partly or fully automated or mechanized transplantation has been developed especially to save man power and to make the work efficient. A pot suitable for such automated transplantation is disclosed in Japanese Patent Publication No. 30805/1980 corresponding to U.S. Pat. No. 4,132,337 and U.K. Pat. No. 1,559,343. This multiple pot consists of individual pots connected in rows by connector portions and is used in the manner described below. First, plants are raised using this multiple pot in normal manner. Then, the multiple pot is separated into individual pots along separation lines which are formed in the connector portions to facilitate the separation, the separation lines extending from one end of the multiple pot. Subsequently, the separated pots are transplanted to a plant. In this way, when plants are raised using this multiple pot, the individual pots can be pulled from one end of the multiple pot while assuming the form of rows. Therefore, the multiple pot can be divided into the individual pots without substantially requiring man power and then they can be transplanted. This enables fully automatic transplantation work.
A method of fabricating the aforementioned multiple pot is disclosed in Japanese Patent Publication No. 11817/1983. Specifically, two wide thin films of a given width are stuck on each other at regular intervals with waterproof paste to form a belt. Notched lines are then formed in portions excluding the stuck portion at one side end so as to extend through the belt, in order to form separation lines. This belt is divided into strips in such a way that each strip has notched and non-notched portions and that the notched line is located at the front end or rear end of the strip. Every other strip is rotated through 180.degree.. Then, the front ends of the notched portions are aligned. Every other stuck portion is shifted such that a half of one stuck portion is placed on a half of a neighboring stuck portion. Thus, a multilayered structure is formed. Applied and unapplied portions are formed on the right portion and on the left portion near the top of each strip such that they alternate with each other. Waterproof paste is applied to the applied portions, while the paste is not applied to the unapplied portions. Water-soluble paste is applied to the other surface, and the whole surface is stuck. As a result, a multiple pot is fabricated which has separation lines including successive notches either at the upper side or at the lower side of each connector portion between individual pots.
The above-described known method involves manifold manufacturing steps and is complex. Hence, uninterrupted fabrication of multiple pots is difficult to realize. Thus, a more efficient manufacturing method has been desired.
In the known multiple pot disclosed in the above-cited Japanese Patent Publication No. 30805/1980 corresponding to U.S. Pat. No. 4,132,337 and U.K. Pat. No. 1,559,343, the individual pots are connected together so as to form rows. The structure of this multiple pot is preferable, because it allows transplantation of seedlings in pots by an automatic transplanter, but there remains room for improvement. That is, the growth of roots extending across the side walls of pots after transplantation must be improved. When the multiple pot is unfolded, the individual pots become nonuniform in shape. Also, the resistance encountered at this time must be reduced.
The growth of roots extending across the side walls of pots after transplantation is considered to be important, because it affects the activity of the roots after transplantation. Accordingly, various contrivances have been devised. In the contrivance disclosed in Japanese Utility Model Publication No. 12362/1976, holes are formed in the side wall of each individual pot. In the contrivance disclosed in Japanese Patent Publication No. 30328/1980, a paper pot is specially treated so that a part of the pot may decompose easily. However, in the former structure, water-soluble paste intrudes through the holes when individual pots are assembled, thereby hindering unfolding. In the latter case, it is considerably difficult to prepare raw paper which can be used irrespective of soil conditions and farm environment and hence it is not always satisfactorily used.
A known means for reducing the resistance encountered during unfolding is disclosed in Japanese Patent Publication No. 11287/1980, where discontinuous notches are formed along the folded portions of pots which correspond to the edges created when the multiple pot is unfolded. These notches are plugged up, depending on the kind of the water-soluble paste used. Then, a coating of the dried paste is formed. Further, water-soluble paste intrudes into the notches, resulting in excessive attachment of the thin films.
Because of these circumstances, a multiple pot is desired which promotes growth of roots after transplantation independent of soil conditions and farm environment and which reasonably reduces resistance encountered during unfolding.